Platform door systems that may be used to separate track areas from platform areas are becoming more and more important for a variety of reasons. Most importantly, their use can increase safety considerably, because they thus render the track area entirely inaccessible to travelers, who therefore cannot fall onto the tracks in front of arriving trains. Secondly, they also serve as an energy efficient way to ensure air conditioning of the platform area.
Simple platform door systems are aligned with certain train models, and include platform doors at fixed locations along the platform opposite which the train doors are expected to be positioned when the train is at a standstill.
Particularly when trains are controlled manually, it is not always possible to stop the train in exactly the required position, and consequently when the train has stopped the positions of the platform doors are not exactly opposite the locations of the train doors. If different trains are used, in which the doors are positioned differently, it often happens that the platform doors and the train doors are completely out of alignment.
Various attempts have already been made to solve the above problems, both from the point of view of the platform door systems, which are sometimes referred to as “full height” systems and may completely cover the platform as far as the track, and with platform guardrail systems, which are sometimes referred to as “half height” or “lower height” systems because they make use of a railing extending along the platform only at about waist height.
JP 2005 335451 A suggests a guardrail system with fence cases that are movable along the platform, the sliding fences being movable into and out of said cases to create or close passages between the movable fence cases. EP 2 500 225 A1 suggests an enhancement of this system, in which telescope-like fence elements extend out of the fence cases so that the spaces between each two adjacent movable fence cases that are closable by the sliding fences may be enlarged, and wider passages may be created between the fence cases. In both systems, the positions at which the passages to the trains can be created are modified by moving the fence cases. Both systems intentionally make use of only a single guardrail for the track, to ensure that the driver of the vehicle, for example, has an unobstructed view of the track. However, such systems cannot prevent people from falling over the guardrail and onto the track, or climbing over the railing. Furthermore, such systems do not allow the platform to be partitioned off from the track, which is often desirable for ventilation and air conditioning purposes. However, a particular drawback associated with these systems is that in order to modify the passages that can be created by the fences for a new train door configuration all parts of the guardrail, including the fence case, must be moved along the platform. However, experience has shown that it is precisely when platforms are overcrowded that people often lean on structures they believe to be fixed in place, which can result in accidents such as falling or getting hands or feet caught between elements. The risk of becoming caught in this way is greater when telescopic fence elements are used.
DE 692 05 097 T2 discloses a “full height” system, in which many sliding door panels are arranged side by side along the platform so as to form an almost unbroken closed surface in the closed state, similar to the surface formed by the train doors and the outer bodywork of the train. Then, depending on where the train doors are located when the train is stopped at the platform, a special opening mechanism moves certain of the sliding door panels out of the closed surface into a separate opening plane in which the selected sliding door panels can move. While this system allows any of a plurality of adjacent sliding door panels to open and form a passage, the places where the sliding door panels are located are determined in advance, so passages can only be created at predetermined, discrete locations. It is therefore not possible to match the passage created on the platform exactly with the positions of the train doors using this system.
Document WO 2008/149246 also suggests a “full height” platform door system comprising fixed posts and movable sliding door panels arranged along the platform, wherein the sliding door panels are of such a size that they each extend over slightly more than half of the area between the posts in the closed position, and wherein they extend in parallel planes slightly offset relative to each other and slightly overlap each other in the closed state. With this system, it is thus possible for passages to be created between the posts at various positions by opening the sliding door panels to different degrees. However, this system is associated with a number of problems that have proven to be extremely disadvantageous in practice. In order to prevent passengers from getting caught between the platform door and the train door, the train doors and the platform doors should be closed simultaneously. But since train doors, especially those used in mass transportation vehicles such as underground trains in large cities, where the use of platform door systems is most beneficial, usually open and close very quickly, the very large sliding door panels on the platform must also be moved and braked quickly. Since such door panels usually contain large areas of glass, a considerable weight must be accelerated and decelerated again with great precision, which is no simple matter. Because the door panels in this system are necessarily of considerable size, the panels when opening swing past the posts and into the area where the adjacent door panels are then moving in the opposite direction. This can lead to trapping of the fingers of the unmindful passengers who are leaning against or holding onto a sliding door as it opens. It has also proven difficult to detect a certain closed position between the two sliding door panels extending between the two parallel, slightly offset planes that form a passage.